Plant Growth-Promoting Microbes for Sustainable Crop Production (A Review)

Abstract

Plant growth-promoting microbes (PGPM) are a group of beneficial microorganisms that stimulate plant growth directly by improving nitrogen fixation, phosphate solubilization, mineral uptake/transport, plant growth hormone/regulator metabolism, and indirectly by systemic induced/acquired resistance by salicylic/jasmonic acid production. These microorganisms can act against plant pathogens by exoenzymes, secondary metabolite production, osmolyte production in abiotic stress. Pseudomonas/Bacillus spp. are the most versatile plant growth-promoting bacteria (PGPB). The PGPMs can be used as rhizome-remediators, phytostimulators, biofertilizers, and stress controllers. The PGPMs’ treatment promotes the growth of several plants such as lentils, peas, cucumbers, and soybeans. Their availability depends largely on interactions between microorganisms in soil and the ecto- and endophytes of root, stem, and leaf. PGPMs affect positively to plant growth, nutrient uptake, biotic resistance, and disease-causing pathogens, and contributes to an increase in yield in several crop plants. This review extensively covers all these aspects of various ways adapted by the PGPM to stimulate positively plant growth effects. PGPB influence phosphorus (P) homeostasis to induce beneficial effects in plants. The review introduces the topic from the perspectives of P and their relation with PGPB. It interlinks the entomopathogens and endophytes with the PGPBs’ regulation of plant growth. Different mechanisms and techniques of P solubilization by the PGPB are discussed. Followingly, the genetics and metagenomics of P solubilization are explained. This review opens various perspective points for further research for enhancing plant growth, strengthening sustainable agriculture of food crops.